Voltage converter having light-load control

ABSTRACT

Voltage converter having light-load control. In some embodiments, a voltage converter can be configured to receive an input voltage and generate a regulated voltage. Such a voltage converter can include a determining unit configured to determine whether the voltage converter is in a first load state. The voltage converter can further include a driving unit in communication with the determining unit, and be configured to generate a first driving signal when the voltage converter is in the first load state. The voltage converter can further include a switching unit in communication with the driving unit, and be configured to route the first driving signal to a control element of the voltage converter when the voltage converter is in the first load state, and be further configured to route a second driving signal to the control element when the voltage converter is in a second load state.

INCORPORATION BY REFERENCE TO ANY PRIORITY APPLICATIONS

Any and all applications for which a foreign or domestic priority claimis identified in the Application Data Sheet as filed with the presentapplication are hereby incorporated by reference under 37 CFR 1.57. Thisapplication is a continuation of U.S. application Ser. No. 14/291,400filed May 30, 2014, entitled LIGHT-LOAD CONTROL DEVICE, LIGHT-LOADCONTROL METHOD, AND VOLTAGE CONVERTER, the benefit of the filing date ofwhich is hereby claimed and the disclosure of which is hereby expresslyincorporated by reference herein in its entirety.

TECHNICAL FIELD

The present application relates to electronic technology field, and moreparticularly, to a light-load control device, light-load control methodand a voltage converter.

BACKGROUND

An electronic apparatus is generally equipped with a power supply havinga specific voltage, e.g., a battery in the electronic apparatus is ableto supply voltages of 3.9-4.5V. However, various modules of theelectronic apparatus require different supply voltages, e.g., an analogpower amplifier may request a power voltage of 3.5V, and a digitalprocessing module may require different power voltages such as 1.8 v and5V. In order to ensure normal operations of the various modules in theelectronic apparatus, a voltage converter is typically required toconvert a direct current (DC) voltage level (e.g., a voltage from thebattery) to another different DC voltage required by the variousmodules, namely, to convert a specific input voltage Vin to a differentoutput voltage Vout.

In an existing voltage converter, for example, electric energy at theinput end is temporarily stored in an inductor and/or a capacitor (i.e.,performing a charging process), and then released at the output end atdifferent voltages (i.e., performing a discharging process), thereby theinput voltage Vin is converted to a required output voltage Vout. Thecharging process and discharging process are controlled by a controlelement (such as a switch), which is driven by a driving signal. As anexample, the charging process corresponds to a conducting time when thedriving switch is turned on for charging, and the discharging processcorresponds to an open time when the driving switch is turned off fordischarging. The conducting time corresponds to a pulse width of thedriving signal.

Although an ideal voltage output of the voltage converter is a DCvoltage, the charging and discharging processes therein result in asubtle fluctuation in the actual output voltage, which is shown in thefrequency domain where the output voltage is not an ideal zero frequencycomponent but possesses different frequency components. However, when aelectronic module powered by the voltage converter includes a radiofrequency circuit used for transmitting a radio frequency signal, theoutput voltage of the voltage converter may disturb the radio frequencysignal if the frequency component in the output voltage of the voltageconverter is approximate to the frequency of the radio frequency signal.Therefore, when a load of the voltage converter is an electronic modulehaving a radio frequency circuit, it is desirable to control the signalcomponent (or noise component) capable of disturbing the load in theoutput voltage of the voltage converter. In other words, the voltageconverter is under a low-noise mode through controlling the noise in theoutput voltage of the voltage converter.

In a voltage converter under low-noise mode, the driving signal of thecontrol element therein can be controlled for reducing the noisecomponent in the output voltage of the voltage converter, so that thecontrol element is relatively smoothly switched from on to off, and/orswitched from off to on. For example, the driving signal of the controlelement can be controlled to improve a cut-off voltage of a triodeserving as a control element. When the load (e.g., the resistance of theelectronic module) powered by the voltage converter is heavy, thelow-noise characteristic of the voltage converter can supply power forthe electronic module without disturbing the radio frequency signal ofthe electronic module as far as possible. However, when the load poweredby the voltage converter under the low-noise mode is light and evenzero, current flow can still appear on the control element, therebycausing unnecessary power consumption. Therefore, it is desirable toreduce the static current when the voltage converter under the low-noisemode has light load.

SUMMARY

Various aspects of the present application may relate to a light-loadcontrol device applied to a voltage converter; a light-load controlmethod applied to the voltage converter; the voltage converter; anelectronic module including this voltage converter, and electronicapparatus, etc.

A light-load control device of the present application can be applied toa voltage converter, where the voltage converter has a control element,which is able to control the charging and discharging of the voltageconverting circuit by being driven by a specific driving signal, so asto convert an input voltage Vin to an output voltage Vout, where thespecific driving signal is generated by adjusting a basic driving signalof the control element, and the voltage converter can stop workingtemporarily (e.g., stop charging and discharging) under the control ofthe control element when the powered load is under the light-load state.

A light-load control device of the present application includes: adetermining unit, for determining whether the voltage converter is underlight-load state, and generating a discontinuous conduction signalindicating whether the voltage converter is disabled when the voltageconverter is under the light-load state; a light-load driving unit,which is capable of generating a light-load driving signal on the basisof a basic driving signal of the control element, the light-load drivingsignal being capable of reducing power consumption of the voltageconverter in the light-load state; a switching unit, for providing thebasic driving signal to the light-load driving unit when thediscontinuous conduction signal indicates that the voltage converter isdisabled, and driving the control element by use of the light-loaddriving signal instead of the specific driving signal. When thediscontinuous conduction signal indicates that the voltage converter isenabled, the switching unit carries out the switching and drives thecontrol element by using the driving signal, instead of using thelight-load driving signal.

In a technical solution of the present application, when the voltageconverter is under the light-load state, the specific driving signal ofthe control element can be replaced with the light-load driving signalto reduce the power consumption in the control element, therebyoptimizing a performance of the voltage converter by using a properdriving signal according to the load of the voltage converter.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to illustrate the technical solution more clearly, the drawingsprovided for description of the embodiments or the prior art shall bebriefly explained as follows. The drawings in the following descriptionare merely some embodiments of the present application, from which oneordinarily skilled in the art still can obtain other drawings.Throughout respective drawings, same reference signs typically denotesame components.

FIG. 1 is a schematic diagram which illustrates a voltage converter towhich a light-load driving device of the present application is applied;

FIG. 2 schematically illustrates a circuit diagram of a specific controlunit being a low-noise control unit in FIG. 1;

FIG. 3 is a schematic diagram which illustrates the connection of thelight-load driving device of the present application in the voltageconverter of FIG. 1.

FIG. 4 is a block diagram which schematically illustrates the light-loaddriving device in FIG. 3.

FIG. 5 schematically illustrates a connection relationship of a controlunit in the light-load driving device of the present application;

FIG. 6 illustrates a schematic circuit diagram of the light-load drivingdevice of the present application implemented based on the low-noisecontrol unit in FIG. 2;

FIG. 7 illustrates a schematic diagram of the relationship between agate-source electrode voltage Vgs and a drain current Id when a triode101 is of a NMOS transistor;

FIG. 8 illustrates a simulation result of applying the light-loaddriving device in FIG. 6 to the voltage converter;

FIG. 9 illustrates a flow diagram of a light-load driving method appliedto the voltage converter of the present application.

DETAILED DESCRIPTION

A voltage converter involved in the present application may be a boostconverter, a buck converter, a boost-buck converter, etc. The voltageconverter is used for converting the power voltage into voltagesutilized by various electronic modules in an electronic apparatus; theelectronic modules can be, for example, a radio frequency amplifier, adisplay, etc. The electronic apparatus including the electronic modulescan be, for example, a mobile phone, a tablet computer, a display, aneBook reader, a portable digital media display, and the like. Type ofthe voltage converter, the powered electronic module, and the electronicapparatus applied thereto do not constitute a limitation to the presentapplication.

FIG. 1 is a schematic diagram which illustrates a voltage converter towhich a light-load driving device of the present application is applied.The voltage converter 100 shown in FIG. 1 converts the input voltage Vinto the output voltage Vout, and the output voltage Vout can supply powerto a load. The voltage converter 100 may comprise a control element,such as a triode in FIG. 1. A specific driving signal for driving thecontrol element is generated by adjusting a basic driving signal of thecontrol element, which operates upon being driven by the specificdriving signal so that the output voltage Vout has a specificperformance.

As shown in FIG. 1, the voltage converter 100 includes a voltageconverting circuit 110, which comprises a control element which controlsthe charging and discharging operations of the voltage convertingcircuit 100 upon being driven by a specific control signal Sc; a firstdriving unit 120, for generating a first basic driving signal Sd1,wherein the first basic driving signal Sd1 drives the control element toperform a basic control operation; a specific control unit 130, foradjusting the first basic driving signal from the first driving unit 120so as to generate a specific driving signal, wherein the specificdriving signal is used for driving the control element so that thevoltage converter has the specific performance.

The voltage converting circuit 110 in FIG. 1 is a buck convertingcircuit; the control element driven by the specific control signal Sc isthe triode 101 in FIG. 1. The triode 101 is an element related to thetechnical solution of the present application, and it is described inthe example context where only the power consumption of the triode 101needs to be controlled when the voltage converter is under thelight-load state.

In addition to the triode 101, the voltage converting circuit 110 mayfurther include other control elements, such as a triode 102 in FIG. 1,which is connected between a port of the input voltage Vin and thetriode 101 and cooperates with the triode 101 to control the chargingand discharging operations of the voltage converting circuit 110. In acase where the triode 101 is a NMOS transistor and the triode 102 is aPMOS transistor, the driving signal for the triode 102 (namely, a secondbasic driving signal Sd2) can be the same as the first basic drivingsignal Sd1 from the first driving unit 120; in a case where the triode101 and the triode 102 are transistors of same type (such as the NMOStransistor or the PMOS transistor), the second basic driving signal Sd2of the triode 102 can be obtained by reversing the first basic drivingsignal Sd1. As described above, the control element of the voltageconverter further includes the triode 102. In other embodiments, thetriode 102 may need to be controlled to achieve the above or otherspecific performances of the voltage converter; correspondingly, thetriode 102 can be controlled by using another specific control unit, andthe another specific control unit can adjust the second basic drivingsignal Sd2 so as to generate another specific driving signal applied tothe triode 102.

In addition to the triodes 101 and 102, the voltage converting circuit110 further includes: an inductor 103 having a first end which islocated at a joint of the triodes 101 and 102, and a second end which isconnected to a port of the output voltage Vout; a capacitor 104 having afirst end which is connected to the second end of the inductor 103, anda second end which is grounded to facilitate a stable output of theoutput voltage Vout.

During the charging process, the triode 101 is turned off and the triode102 is turned on, and the inductor 103 is charged to generate inductivecurrent; since the input voltage Vin is direct current, the inductivecurrent on the inductor 103 linearly increases at a certain rate;correspondingly, current flows through both ends of the load, therebyhaving the output voltage. During the discharging process, the triode101 is turned on while the triode 102 is turned off; due to the holdingproperty of the inductive current, the current flowing through theinductor 103 slowly decreases from a value when the charging process isfinished until the next charging process starts or the current valuedeclines to 0; correspondingly, the inductor L starts to charge thecapacitor C, thereby maintaining the output voltage Vout.

The voltage converting circuit 110 in FIG. 1 is a buck convertingcircuit, and it can be a boost converting circuit or a boost-buckconverting circuit. The boost converting circuit is provided with thecontrol elements which are similar to the triodes 101 and 102, and theboost-buck converting circuit may have a greater number of controlelements.

The first driving unit 120 in FIG. 1 generates the first basic drivingsignal Sd1, and the first basic driving signal Sd1 drives the controlelement to perform a basic control operation. For example, the outputvoltage Vout and a reference voltage (which corresponds to an expectedoutput voltage) are compared by an error amplifier in the voltageconverter 100; the first driving unit 120 generates the first basicdriving signal Sd1 for controlling the turning-on time and cut-off timeof the triode 101 based on the comparison result of the error amplifier.For example, when the first basic driving signal Sd1 is at a low level(e.g., zero), the triode 101 is controlled to be turned off; when thefirst basic driving signal Sd1 is at a high level (e.g., 4V), the triode101 is controlled to be turned on. As an example, the first driving unit120 can be a driving unit of pulse width modulation (PWM), a drivingunit of pulse frequency modulation (PFM), etc., which may be achieved byusing any existing or future technology; and the specific implementingway will not limit the embodiment of the present application.

As described above, the second basic driving signal Sd2 in the buckconverter can be the same as the first basic driving signal Sd1 orobtained through performing reverse phase on the first basic drivingsignal Sd1 depending on the types of triodes 101 and 102. Alternatively,the first driving unit 120 can further generate basic driving signalsapplied to the triodes 101 and 102, respectively; or the first drivingunit 120 only generates the first basic driving signal Sd1 applied tothe triode 101, and generates the second basic driving signal Sd2applied to the triode 102 by using other driving unit.

The specific control unit 130 adjusts the first basic driving signal Sd1from the first driving unit 120 to generate a specific driving signalSc, and the specific driving signal Sc is used for driving the controlelement so that the voltage converting circuit 110 has specificperformance. Generally, the first basic driving signal Sd1 can drive thecontrol element such as the triode 101 so that the voltage converter 100can perform voltage conversion. However, the electronic module (i.e.,load) powered by the voltage converter 100 may have different demands.For example, when the electronic module is provided with a radiofrequency circuit for transmitting a radio frequency signal, it isrequired or desirable to reduce the radio frequency component in theoutput voltage Vout of the voltage converter 100, and the radiofrequency component is typically noise for the radio frequency signal inthe radio frequency circuit. Some electronic modules require high powerstability, and it is desired that the output voltage in the voltageconverter 100 has small wave, etc. The specific driving signal can begenerated by adjusting or additionally processing the first basicdriving signal Sd1, and the first basic driving signal Sd1 can beadjusted by the specific control unit 130, thereby meeting differentdemands of different electronic modules.

With reference now to FIG. 2, a schematic implementation where thespecific control unit is a low-noise control unit is described, whereinthe low-noise control unit can reduce the noise in the output voltageVout of the voltage converter 100. The low-noise control unit processesthe first basic driving signal Sd1 to generate the specific drivingsignal, which is low-noise control signal Sln, and the low-noise controlsignal Sln drives the control element so that the output voltage Vouthas low noise.

FIG. 2 schematically illustrates a circuit diagram of a specific controlunit being a low-noise control unit in FIG. 1. As an example, when thelow-noise control signal Sln of the low-noise control unit is at highlevel, the triode 101 (e.g., the control element in the voltageconverting circuit) is driven to be turned on; when it is at low level,the triode 101 is driven to be turned off, and it switches between highlevel and low level to facilitate driving of the triode 101. Comparedwith the first basic driving signal Sd1, the low-noise control signalSln of the low-noise control unit increases the low level voltage of thefirst basic driving signal Sd1, so that the switch between the highlevel and the low level is smoother, thereby reducing the radiofrequency component in the output voltage.

As shown in FIG. 2, the low-noise control unit comprises triodes 131,132, 133 and current source 134. The triode 131 is a PMOS transistor;triodes 132 and 133 are NMOS transistors. A source electrode of thetriode 131 is connected to an input end of the current source 134, agate electrode and a drain electrode of the triode 131 are respectivelyconnected to a gate electrode and a drain electrode of the triode 132; asource electrode of the triode 132 is connected to a drain electrode ofthe triode 133, and a gate electrode of the triode 133 is connected toan output end of the current source 134; a source electrode of thetriode 133 is grounded, and the current source 134 is connected to apower voltage Vdd to operate; the power voltage Vdd can be, for example,the input voltage Vin of the voltage converter. The output end of thecurrent source 134 is connected with the drain electrode of the triode131 through a lead. Alternatively, the output end of the current source134 is connected with the drain electrode of the triode 133 through aresistor.

FIG. 2 shows that when the first basic driving signal Sd1 is at lowlevel, the triode 131 is turned on while the triode 132 is turned off,and voltage of the low-noise driving signal Sln output by the low-noisecontrol unit is equal to the power voltage Vdd, and is at high level;when the first basic driving signal Sd1 is at high level, the triode 131is turned off while the triode 132 is turned on; the triode 133, thecurrent source 134, and the triode 101 in the voltage converting unit110 form a mirror current source, so that a voltage level greater thanzero is formed at the drain electrode end of the triode 133, namely, thelow-noise driving signal is at low level. The low level of the low-noisedriving signal Sln is greater than zero but less than a thresholdvoltage of the triode 101 in the voltage converting circuit 110, therebyincreasing the low level voltage of the low-noise driving signal. Thatis to say, when the basic driving signal Sd1 is at low level, thelow-noise control unit outputs a low-noise driving signal having highlevel; when the basic driving signal Sd1 is at high level, the low-noisecontrol unit outputs a low-noise driving signal having low level. Thelow level is increased to be greater than zero.

The implementation of the low-noise control unit depicted in FIG. 2 isonly schematic, and it can be implemented by adopting other circuits inpractice. Alternatively, the low-noise control unit can reduce noise bydecreasing the voltage at high level; correspondingly, the circuit ofthe low-noise control unit also will change.

When the load powered by the voltage converter 100 is more than apredetermined value and it is a medium or heavy load, the voltageconverter 100 shown in FIG. 1 will perform the charging and dischargingoperations continuously so as to output an output voltage with lownoise. However, when the load powered by the voltage converter 100 isless than the predetermined value and it is a light load and even zeroload (namely, in light-load state), the voltage converter 100 may pausethe charging and discharging operations on the principle of energyconservation, at this moment, the triodes 101 and 102 in the buckconverting unit are turned off. When the triode 101 is turned off,current still exists in the triode 101 since the low-voltage drivingsignal output from the specific control unit 130 may not be zero,thereby consuming power unnecessarily. It should be noted that, indifferent voltage converters, the judging condition of light-load statethereof will also change, namely, the predetermined value may changebetween different voltage converters.

FIG. 3 is a schematic diagram which illustrates the connection of thelight-load driving device of the present application in the voltageconverter of FIG. 1. FIG. 3 adopts the same reference numbers togenerally denote the same or similar parts in FIG. 1. Different fromFIG. 1, a light-load driving device 150 is added in FIG. 3. Thelight-load driving device 150 can determine whether the voltageconverter is under the light-load state, generate a discontinuousconduction signal DCS for indicating whether the voltage converter isdisabled when the voltage converter is under the light-load state, stopthe specific control unit 130 in accordance with the discontinuousconduction signal DCS, and generate a light-load driving signal on thebasis of the first basic driving signal Sd1 to drive the control elementin the voltage converting unit 110 so as to reduce the power consumptiontherein, thereby optimizing the performance of the voltage converter 100by using proper driving signal according to the load of the voltageconverter. If the triode 102 (i.e., another control element) in thevoltage converting unit 110 in the FIG. 3 is driven by another specificdriving unit, another light-load driving device can be adopted togenerate a light-load driving signal with respect to the triode 102; thetriode 102 is driven by using the light-load driving signal under thelight-load state, so as to reduce the power consumption of the triode102 under the light-load state.

FIG. 4 is a block diagram which schematically illustrates the light-loaddriving device 130 in FIG. 3. The light-load driving device 150 can beapplied to the voltage converter 100 depicted in FIG. 1. As shown inFIG. 4, the light-load driving device 150 includes: a determining unit151, for determining whether the voltage converter is under thelight-load state, and generates a discontinuous conduction signal DCS toindicate whether the voltage converter is disabled when the voltageconverter is under the light-load state; a light-load driving unit 152,which can generate a light-load driving signal based on the basicdriving signal of the control element (e.g., the triode 101 in FIG. 1)in the voltage converter, wherein the light-load driving signal is ableto reduce the power consumption of the voltage converter under thelight-load state; a switching unit 153, for providing the first basicdriving signal to the light-load driving unit 152 when the discontinuousconduction signal DCS indicates that the voltage converter is disabled,and replacing the specific driving signal Sc with the light-load drivingsignal to drive the control element. The switching unit 153 also canprovide the first basic driving signal to the specific control unit 130when the discontinuous conduction signal DCS indicates that the voltageconverter is enabled, and replace the light-load driving signal with thespecific driving signal Sc to drive the control element.

The determining unit 151, for example, can receive load stateinformation from the electronic module (i.e. load) powered by thevoltage converter 100, determine whether the voltage converter is underthe light-load state according to the received load state information,and generate the discontinuous conduction signal DCS. When the voltageconverter is under the light-load state, the discontinuous conductionsignal can be generated according to a value of the load (i.e. loadvalue). For example, when the discontinuous conduction signal disablesthe voltage converter periodically, the smaller the load value in thelight-load state is, the longer the lasting time of disabling thevoltage converter in the discontinuous conduction signal is; the greaterthe load value in the light-load state is, the shorter the lasting timeof disabling the voltage converter in the discontinuous conductionsignal is. Alternatively, the determining unit 151 further can determinewhether the voltage converter is under the light-load state according tothe operating state of the voltage converter 100. For example, in thebuck converting unit 110 as shown in FIG. 1, the determining unit 151can determine whether the voltage converter is under the light-loadstate when the output voltage Vout is greater than the referencevoltage; when the voltage converter is under the light-load state, thediscontinuous conduction signal for indicating that the voltageconverter is disabled is generated if the triodes 101 and 102 in thebuck converting unit are turned off, so that the switching unit isswitched to drive the control element with the light-load drivingsignal; if any one of the triodes 101 and 102 is not turned off, thediscontinuous conduction signal for indicating that the voltageconverter is enabled is generated, so that the switching unit isswitched to drive the control element with the specific driving signal.The specific method of determining the load state by the determiningunit 151 will not limit the present application.

The light-load driving unit 152 can generate the light-load drivingsignal by proper methods in view of the reason that the control elementgenerates power consumption under the light-load state, so as to reducethe power consumption of the control element under the light-load state.For example, when unnecessary power consumption of the control elementunder the light-load state is caused by high level of its drivingsignal, the level of the driving signal of the control element should bedecreased; when the unnecessary power consumption of the control elementunder the light-load state is caused by fluctuation of the drivingsignal, a smoother driving signal is provided. The basic driving signalof the control element is a given signal in the voltage converter, andthe light-load driving unit 152 can more conveniently generate thelight-load driving signal by using the basic driving signal. Forexample, when there are excessive power consumptions in the controlelement since the specific control unit 130 increases the low level ofthe first basic driving signal Sd1, the light-load driving unit 152under the light-load state can directly use the first basic drivingsignal Sd1 as the light-load driving signal of the control element, or ahigh level signal is inverted by a inverter so as to generate a lowlevel signal which is more approximate to zero, thereby reducing thepower consumption of the control element under the light-load state.

When the discontinuous conduction signal indicates that the voltageconverter is disabled, the switching unit 153 provides the first basicdriving signal to the light-load driving unit 152, and replaces thespecific driving signal Sc with the light-load driving signal to drivethe control element.

FIG. 5 schematically illustrates a connection relationship of theswitching unit 153 in the light-load driving device 150 of the presentapplication. As shown in FIG. 5, the switching unit 153 comprises: afirst switch 153S1, for providing the first basic driving signal Sd1 tothe light-load driving unit 152 when the discontinuous conduction signalindicates that the voltage converter is disabled, and providing thefirst basic driving signal Sd1 to the specific control unit 130 when thediscontinuous conduction signal indicates that the voltage converter isenabled; a second switch 153S2, for providing an output of thelight-load driving unit 152 to the control element when thediscontinuous conduction signal indicates that the voltage converter isdisabled, and providing the output of the specific control unit 130 tothe control element when the discontinuous conduction signal indicatesthat the voltage converter is enabled. The first switch 153S1 can be asingle-pole double-throw switch, or two independent 1×1 switches;similarly, the second switch 153S2 can be a single-pole double-throwswitch, or two independent 1×1 switches.

It is shown above that in one or more technical solutions of thisapplication, the specific driving signal for the control element can bereplaced with the light-load driving signal so as to reduce the powerconsumption in the control element when the voltage converter operatesdiscontinuously under the light-load state, thereby optimizing theperformance of the voltage converter by using the proper driving signalaccording to the load of the voltage converter.

FIG. 6 illustrates a schematic circuit diagram of the light-load drivingdevice of the present application implemented based on the low-noisecontrol unit in FIG. 2. Shown as FIG. 6, switches 153 a, 153 b, 153 care added in the low-noise control unit in FIG. 2; the switches 153 a,153 b, 153 c jointly form the switching unit 153 in FIG. 0.4. By usingthe switching unit 153, when the discontinuous conduction signal DCS ofthe determining unit 151 indicates that the voltage converter isenabled, the switches operates to change the circuit diagram in FIG. 6to be the circuit diagram shown in FIG. 2, thereby generating thelow-noise driving signal; when the discontinuous conduction signal DCSof the determining unit 151 indicates that the voltage converter isdisabled, the light-load driving device employs the triodes 131, 132 and133 therein to form an inverter; the formed inverter can invert thefirst basic driving signal to generate a light-load driving signal S11.The low voltage of the light-load driving signal is lower than the lowvoltage of the low-noise driving signal, thereby reducing the powerconsumption of the control element in the voltage converting circuit 110under the light-load state. In FIG. 6, the light-load driving unit 152is formed by an existing component in the low-noise control unit, sothat cost is saved.

As shown in FIG. 6, one end of the switch 153 a is connected to anoutput end of the current source 134, and the other end thereof isconnected to the gate electrode of the triode 133 through the switch 153c; the switch 153 a is open when the discontinuous conduction signal DCSof the determining unit 151 indicates that the voltage converter isdisabled while it is closed when the discontinuous conduction signal DCSindicates that the voltage converter is enabled; the switch 153 b issituated between the gate electrode of triode 132 and the gate electrodeof the triode 133; the switch 153 b is turned off when the discontinuousconduction signal DCS of the determining unit 151 indicates that thevoltage converter is disabled while it is turned on when thediscontinuous conduction signal DCS indicates that the voltage converteris enabled; one end of the switch 153 c is connected to the gateelectrode of the triode 133, and the other end thereof is connected tothe output end of the current source 134 via the switch 153 a; theswitch 153 c is open when the discontinuous conduction signal DCS of thedetermining unit 151 indicates that the voltage converter is disabledwhile it is closed when the discontinuous conduction signal DCSindicates that the voltage converter is enabled.

The switches 153 a, 153 b, and 153 c can be controlled as below. Thediscontinuous conduction signal DCS generated by the determining unit151 is inverted, to generate an inverted discontinuous conduction signal(DCSB); the switches 153 a and 153 c are controlled by the inverteddiscontinuous conduction signal DCSB, and the switch 153 b is controlledby the discontinuous conduction signal DCS.

When the discontinuous conduction signal DCS of the determining unit 151indicates that the voltage converter is enabled, the switches 153 a and153 c are closed, and the switch 153 b is open; the circuit diagram inthe FIG. 6 is equivalent to that in FIG. 2, and low-noise driving signal(i.e., Sln) is generated on the basis of the first basic driving signalSd1; when the discontinuous conduction signal DCS of the determiningpart 151 indicates that the voltage converter is disabled, the switches153 a and 153 c are open, and the switch 153 b is closed, the triodes131, 132 and 133 form an inverter; the inverter inverts the first basicdriving signal Sd1 to generate the light-load driving signal Sl1. Thelow voltage of the light-load driving signal is lower than the lowvoltage of the low-noise driving signal, thereby reducing the powerconsumption of the control element of the voltage converting circuit 110under the light-load state.

With reference now to FIG. 7, the principle of reducing its powerconsumption through reducing gate electrode voltage of the triode 101 isdescribed. FIG. 7 illustrates a schematic diagram of the relationshipbetween a gate-source electrode voltage Vgs and a drain current Id whena triode 101 is of a NMOS transistor.

In FIG. 7, a horizontal axis is the gate-source electrode voltage Vgs ofthe triode 101, and a longitudinal axis is the drain electrode currentId of the triode 101. Since the source electrode of the triode 101 isgrounded, the gate-source electrode voltage of the triode 101 is equalto the gate electrode voltage, namely, the voltage of its driving signalSc or Sl1. Vth in FIG. 7 is a threshold voltage of the triode 101; whenthe gate-source electrode voltage Vgs is more than Vth, the triode 101is turned on; when it is less than Vth, the triode 101 is turned off.When the triode 101 is driven by the specific control signal (e.g., thelow-noise driving signal Sln generated by the light-load driving devicein FIG. 6) generated by the specific control unit 130, the low level ofthe low-noise driving signal Sln is between Vgs1 and Vth in FIG. 7, andis used for reducing the noise in the output voltage Vout of the voltageconverter; when the triode 101 is driven by the light-load drivingsignal Sl1, the low level of the light-load driving signal Sl1 is lessthan Vgs1 in FIG. 7, thus the drain electrode current Id in the triode101 is greatly reduced, and the power consumption of the triode 101under the light-load state is lowered. When the triode 101 is of adifferent type, the graphical representation of FIG. 7 can be properlymodified. For example, when the triode 101 is of a PMOS type, thehorizontal axis in FIG. 7 can be replaced with the source-gate electrodevoltage Vsg.

FIG. 8 illustrates the simulation result of applying the light-loaddriving device in FIG. 6 to the voltage converter. It is assumed thatload of the voltage converter is zero, and its input voltage is 3.8V. InFIG. 8, the panels on the left side show the simulation result of takingcircuit in FIG. 6 as the low-noise control unit by the switching unit153 when the voltage converter is under the light-load state; and thepanels on the right side show the simulation result of taking circuit inFIG. 6 as the light-load driving unit by the switching unit 153 when thevoltage converter is under the light-load state.

In the left and right panels of FIG. 8, the horizontal axis representstime, and the longitudinal axis of FIG. 8(a) represents the gateelectrode voltage of the triode 101; the longitudinal axis of FIG. 8(b)is the drain electrode current of the triode 101; the longitudinal axisof FIG. 8(c) is the discontinuous conduction signal DCS of the voltageconverter 100, wherein when the discontinuous conduction signal DCS islow, the voltage converter is used for performing the charging anddischarging operations; when the discontinuous conduction signal DCS ishigh, the voltage converter is disabled, and the charging anddischarging operations are stopped; the longitudinal axis of FIG. 8(d)is the output voltage Vout of the voltage converter; the longitudinalaxis of FIG. 8(e) is current on the inductor in the voltage converter ofFIG. 3. Since the load of the voltage converter is zero (e.g., thevoltage converter is under the light-load state), the voltage converterdoes not carry out the charging and discharging operations under anideal condition; however, since there is power consumption in thecontrol element of the voltage converter, the discontinuous conductionsignal DCS will become low after a period of time, thus the charging anddischarging operations are carried out.

The simulation result of the panels on the left side of the FIG. 8 showsthat when the discontinuous conduction signal DCS is high, and nocharging and discharging operations are carried out in the voltageconverter, the gate electrode voltage of the triode 101 upon driven bythe specific control unit is 498.8 mV (micro volt) (see the voltagevalue at point M0 on the left side panel of FIG. 8(a)); the gateelectrode voltage of the triode 101 upon driven by the light-loaddriving device 150 is 506.3 pV (pico volt) (see the voltage value atpoint M0 on the right side panel of FIG. 8(a)), the gate electrodevoltage of the triode 101 is greatly reduced. Correspondingly, the drainelectrode current of the triode 101 is reduced from 4.902 μA at thepoint M1 of the left panel of FIG. 8(b) to 10.51 pA at the point M1 ofthe right panel of FIG. 8(b); the charging and discharging operationsexecuted in the voltage converter are also reduced, which can be seenfrom lower low level of the DCS signal on the right side in FIG. 8(c);current on the inductor 103 in the voltage converter is also reducedfrom 4.89 μA at the point M2 on the left side to 126.5 pA at the pointM2 on the right side (refer to FIG. 8(e)). It can be seen that, when thevoltage converter is disabled under the light-load state, the specificdriving signal is replaced with the light-load driving signal to drivethe control element (the triode 101), thus the power consumption of thevoltage converter in the light-load state is reduced, and performance ofthe voltage converter is optimized by using proper driving signalaccording to the load of the voltage converter.

FIG. 9 illustrates a flow diagram of a light-load driving method 900applied to the voltage converter in the present application. Thelight-load driving method 900 can be applied to the voltage convertersas depicted in view of FIG. 1 and FIG. 2, and can be applied to otherconverters including a boost converter, a buck converter, and aboost-buck converter and the like; the voltage converter includes: avoltage converting circuit, which comprises a control element, and thecontrol element controls the charging and discharging operations of thevoltage converting circuit upon driven by the specific control signalSc; a first driving unit, for generating a first basic driving signal,wherein the first basic driving signal drives the control element toperform a basic control operation; a specific control unit, foradjusting the first basic driving signal and generating a specificdriving signal, wherein the specific driving signal is used for drivingthe control element so that the voltage converting circuit has specificperformance.

As shown in FIG. 9, the light-load driving method 900 may include stepsof: determining whether the voltage converter is under the light-loadstate, and generating the discontinuous conduction signal for indicatingwhether the voltage converter is disabled when the voltage converter isunder the light-load state (S910); generating the light-load drivingsignal on the basis of the basic driving signal of the control element,wherein the light-load driving signal can reduce the power consumptionof the voltage converter under the light-load state (S920); when thediscontinuous conduction signal indicates that the voltage converter isdisabled, providing the basic driving signal to the light-load drivingunit, and replacing the specific driving signal with the light-loaddriving signal to drive the control element (S930).

In S910, the load state information may be received from the electronicmodule (or load) powered by the voltage converter, and whether thevoltage converter is under the light-load state can be determined on thebasis of the received load state information; when the voltage converteris under the light-load state, the discontinuous conduction signal isgenerated according to a load value. Alternatively, in S910, whether thevoltage converter is under the light-load state can be determined on thebasis of the operating state of the voltage converter, and thediscontinuous conduction signal is generated. For example, whether thevoltage converter is under the light-load state can be determined in thebuck converting unit shown in FIG. 1 when the output voltage Vout of thevoltage converter is greater than a predetermined reference voltage (thereference voltage corresponds to the expected output voltage); when thevoltage converter is under the light-load state, the discontinuousconduction signal for indicating that the voltage converter is disabledis generated in case that the triodes 101 and 102 in the buck convertingunit are turned off, so as to drive the control element by thelight-load driving unit; if any one of the triodes 101 and 102 is notturned off, the discontinuous conduction signal for indicating that thevoltage converter is enabled is generated, so that the control elementis driven by the specific driving signal.

In S920, the light-load driving signal is generated by methods in viewof the reason that the control element generates power consumption underthe light-load state, so as to reduce the power consumption of thecontrol element under the light-load state. For example, whenunnecessary power consumption of the control element under thelight-load state is caused by too high level of its driving signal, thelevel of the driving signal of the control element is reduced in S920;when the unnecessary power consumption of the control element under thelight-load state is caused by fluctuation of the driving signal, asmoother driving signal is provided in the S920. The basic drivingsignal of the control element is a given signal in the voltageconverter, the light-load driving unit 152 can more convenientlygenerate the light-load driving signal on the basis of the basic drivingsignal.

As an example, when the control element is a NMOS transistor, if thecontrol element has excessive power consumption in the specific controlunit because the voltage converter increases the low level of the firstbasic driving signal, the first basic driving signal can be used as thelight-load driving signal of the control element in S920, therebyreducing the power consumption of the control element under thelight-load state. Alternatively, the light-load driving signal can begenerated by using the existing component in the specific control unitof the voltage converter, thus it saves cost greatly and is convenientto control; the specific example can be referred to the descriptionsabout the triodes 131, 132 and 133 in FIG. 6.

In S930, when the discontinuous conduction signal indicates that thevoltage converter is disabled, the light-load driving signal is providedto the control element by using the switch, and the specific drivingsignal is prohibited. Specific implementation of the switch is describedherein in reference to the switches 153S1 and 153S2 in FIG. 5. In a casewhere the light-load driving signal is generated by using the componentin the specific control unit, a control can be carried out by using thespecific component in the specific control unit as described inreference to the switches 153 a, 153 b and 153 c in FIG. 6. When thediscontinuous conduction signal indicates that the voltage converter isenabled, the basic driving signal can be provided to the specificcontrol unit, and the light-load driving signal is replaced with thespecific driving signal to drive the control element.

In the technical solution of the light-load driving method 900 of thepresent application, the specific driving signal of the control elementis replaced with the light-load driving signal to reduce the powerconsumption in the control element when the voltage converter isdisabled under the light-load state, thus the performance of the voltageconverter can be optimized by using driving signal according to load ofthe voltage converter.

In the various examples described herein, references are made totriodes. It will be understood that such triodes can include transistorssuch as field-effect transistors (FETs). Such FETs can include, forexample, MOSFET devices and/or transistors implemented in other processtechnologies. Other types of transistors can be utilized to implementone or more features of the present disclosure.

A person of ordinary skill in the art can understand that the specificimplementation of the method embodiment as described above can bereferred to the corresponding process in the aforesaid productembodiment, the details are omitted here for convenient and simpledescription.

A person of ordinary skill in the art can appreciate that components andprocess steps of respective examples described in conjunction with theembodiments disclosed herein can be implemented by electronic hardware,or a combination of electronic hardware and software. A person ofordinary skill in the art can achieve the described functions by usingdifferent methods for each specific application, but such achievementshould not go beyond the scope of the present application.

The principle and advantages of the technical solution described abovecan be applied to any voltage converter. The voltage converter may beapplied to various electronic apparatuses. The electronic apparatusesinclude but not limited to electronic products and parts of electronicproducts, electronic testers, etc. The consumer electronic products mayinclude but not limited to smart phone, television, tablet computer,display, personal digital assistant, camera, audio player, memory, etc.Parts of the consumer electronic products may include a multi-chipmodule, a power amplifier module, a voltage converter, etc.

The above described are specific embodiments of the present applicationonly, the scope of the present application is not limited thereto, andany person skilled in the art can easily think of changes orreplacements within the disclosed technical scope of the presentapplication, which should be covered in the protection scope of thepresent application.

What is claimed is:
 1. A voltage converter comprising: a voltageconverting unit having a control element; a determining unit configuredto determine whether the voltage converting unit is in a first loadstate or a second load state; a driving unit in communication with thedetermining unit, the driving unit configured to generate a drivingsignal; and a first control unit configured to provide a first controlsignal to the control element based on the driving signal when thevoltage converting unit is in the first load state; a second controlunit configured to provide a second control signal to the controlelement based on the driving signal when the voltage converting unit isin the second load state, the first control unit and the second controlunit arranged in a parallel manner between the driving unit and thecontrol element; and a switching unit including a first switchimplemented at an output of the driving unit and a second switchimplemented at an input of the control element, the switching circuitconfigured to route the driving signal to the first control unit and thefirst control signal to the control element when the voltage convertingunit is in the first load state, and to route the driving signal to thesecond control unit and the second control signal to the control elementwhen the voltage converting unit is in the second load state.
 2. Thevoltage converter of claim 1 wherein the first load state includes anon-light-load state or an enabled state, and the second load stateincludes a light-load state or a disabled state.
 3. The voltageconverter of claim 2 wherein the first control unit is configured as alow-noise control unit, such that the first control signal provided tothe control element results in an output voltage of the voltageconverting unit having a reduced noise.
 4. The voltage converter ofclaim 3 wherein the output voltage of the voltage converting unit isconfigured to support a radio-frequency circuit.
 5. The voltageconverter of claim 4 wherein the output voltage of the voltageconverting unit is configured to support a transmit operation associatedwith the radio-frequency circuit.
 6. The voltage converter of claim 2wherein the second control unit is configured such that the secondcontrol signal provided to the control element results in the voltageconverting unit having reduced power consumption.
 7. The voltageconverter of claim 1 wherein the first and second switches areconfigured to route the driving signal from the driving unit to thefirst control unit and the first control signal from the first controlunit to the control element when in the first load state.
 8. The voltageconverter of claim 1 wherein the first and second switches areconfigured to route the driving signal from the driving unit to thesecond control unit and the second control signal from the secondcontrol unit to the control element when in the second load state.
 9. Amethod for converting voltage, the method comprising: providing avoltage converting unit having a control element; determining whetherthe voltage converting unit is in a first load state or a second loadstate; generating a driving signal with a driving unit; providing, withfirst and second control units arranged in a parallel manner between thedriving unit and the control element, a first control signal from thefirst control unit or a second control signal from the second controlunit, to the control element based on the driving signal when thevoltage converting unit is in the first load state or the second loadstate, respectively; and routing, with a first switch at an output ofthe driving unit and a second switch at an input of the control element,the driving signal to the first control unit and the first controlsignal to the control element when the voltage converting unit is in thefirst load state, and the driving signal to the second control unit andthe second control signal to the control element when the voltageconverting unit is in the second load state.
 10. The method of claim 9wherein the first load state includes a non-light-load state or anenabled state, and the second load state includes a light-load state ora disabled state.
 11. The method of claim 10 wherein the first controlsignal provided to the control element results in an output voltage ofthe voltage converting unit having a reduced noise.
 12. The method ofclaim 10 wherein the second control signal provided to the controlelement results in the voltage converting unit having reduced powerconsumption.